The United States and Japan will step up their defence cooperation to deal with the threat from nuclear-armed North Korea as tensions in East Asia remain high, officials from the two allies said on Thursday.

Long-delayed Changi book released

Historian Lachlan Grant was examining old war memorial files when he made a remarkable discovery.

It was a series of accounts by former prisoners which should have been published soon after World War II, but weren't.

Eleven folders, containing 51 mostly hand-written essays about aspects of life in Changi prisoner of war camp, were found in a collection labelled "8 Div. Papers".

They were written on the back of Singapore prison records from the 1930s and on paper hand-made in the prison.

Mr Grant was astounded.

"These were amazing stories of life and society in the Changi POW camp," he told reporters in Canberra on Wednesday.

"It was quite clear, reading through them (that) this collection had been put together for a purpose. Then to find out the purpose was for a book which never eventuated. I felt it my duty to take up this challenge."